Get to sleep in the brightest conditions with the Lights Out Sleep Mask, which, according to weblog Cool Tools, helps you go dark almost anywhere.

I was stationed for a couple months in Qatar and am currently stationed in Kuwait. The mask is more effective and comfortable than the other ones I've worn. You can open your eyes no matter the time of day and think it's the darkest time of night. It blocks the light most effectively due to the contour over the nose.